1. Technical Field
The present invention relates to a mask frame to which a mask used in depositing an organic material on a large-sized pattern area is fixed by welding and a method for fixing the mask on the mask frame. More particularly, the present invention relates to a mask frame capable of firmly supporting a mask which is used in depositing an organic material layer so as to fabricate a large-sized organic electroluminescent device of an organic electroluminescent display, the mask being supported without damage to a pattern before welding the mask thereon, and a method of fixing the mask on the mask frame.
2. Related Art
As a general flat panel display, an electroluminescent display is classified into an inorganic electroluminescent display and an organic electroluminescent display according to the materials used for an emission layer. The organic electroluminescent display has attracted attention because it can be driven with a low voltage, is lightweight and thin, has a wide viewing angle, and has a fast response time.
Such an organic electroluminescent display includes an organic electroluminescent device having an anode, an organic material layer and a cathode, each of which is stacked on a substrate. The organic material layer includes an organic emission layer which emits light due to exciton obtained by recombining a hole and an electron. Furthermore, to smoothly transport the hole and the electron to the emission layer and enhance emission efficiency, an electron injection layer and an electron transporting layer can be interposed between the cathode and the organic emission layer, and a hole injection layer and a hole transporting layer can be interposed between the anode and the organic emission layer.
In general, the organic electroluminescent device with this configuration can be fabricated by a physical vapor deposition method, such as vacuum deposition, ion plating, sputtering or the like, and a chemical vapor deposition method using gas reaction. Furthermore, when the organic electroluminescent device is fabricated by such methods, there is need for a mask having a predetermined pattern to stack the organic material layers in a proper place. In this regard, the mask is fixed on a mask frame in a state in which the mask is outwardly tensioned.
In addition, when the mask is fixed to the mask frame by a method, such as welding, it is necessary to employ some type of means for weighing down the tension mask during the fixation process. Such means employed during the fixation process can result in damage to the fine pattern formed on the pattern area of the mask. Thus, there is a need for a process which will not cause such damage to the mask.